The Hawk takes you to a place called Lost Bastille, and those aren't bosses they are normal enemies. There's only one boss in Lost Bastille and it's your next roadblock (or it was mine at least). Right now you want to go to no-man's wharf (which leads to Lost Bastille after, and is the proper way to get to it). To get to the Wharf you continue on down the path of the dragonrider you killed. Make sure you have a torch or two (for the Wharf, don't use them up on the journey there).
As for the boss 2 shotting you, he hits like a truck, but he's easy to avoid so long as you circle him and roll to his back when he attacks. The key to that fight is staying close and keeping on his back. As I said though, he's optional and only required if you want to join the blue sentinel covenant. He gives a nice pack of souls of course, but you can always jump on him after you level up some if you want.